Study On Cycling Performance Of Air-ground Compound Source Heat Pump System

With the development of economic in recent years, the environment has becomeseriously. When the haze struck, clean energy has got more attention. An saving-energyand efficient heat pump usually means that it can take advantage of natural low-energysource, such as air, surface water, groundwater, ground, heat of living and productionand so on. Air and soil are inexhaustible nature of low energy, and heat pump systemhas been widely used. However, the application of single-stage air source heat pumpand single-stage ground source heat pump in the northern region is limited in manyareas. At low outdoor temperature air source heat pump is easily caused the low unitcoefficient of performance decline; and ground source heat pump caused soiltemperature imbalance greatly and reduced the operating efficiency of the unit in thenorthern region that the heating load is greater than the cooling load.This paper presents an air-ground compond heat pump system,makingsingle-stage air source heat pump and single-stage ground source heat pumpcombination, this system can change with local realities and outdoor air temperature,and adjust working patterns flexiblely so that the system can run respectively in fouroperating modes:single-stage compressed ground source heat pump+single-stagecompressed air source heat pump, compound source heat pump+single-stagecompressed air source heat pump,compound source heat pump+single-stagecompressed ground source heat pump+single-stage compressed air source heatpump,single-stage compressed ground source heat pump+compond source heatpump+single-stage compressed air source heat pump, and the system expands the application of the single-stage air source heat pump and single-stage ground sourceheat pump.Taking Hohhot and Shenyang as examples, for typical building types in the tworegions, when the recharge amount in summer being equal to20%~100%of the totalheat consumption of the building in winter, we get calculations and analysis at the fouroperating models. At different recharge amounts we get temperature demarcation pointin typical buildings of the two regions under four operating modes, then be based onthe temperature demarcation point can be switched the heat pump operation mode.Thestudy also found that: although each region has a different type of construction,thetemperature demarcation point and SEER almost the same in the same rechargeamount. Considering two factors SEER and the initial investment, the overallperformance of operation mode II and III are better, and also are more suitable for thenorthern region.